Rembrandt van Rijn, The Dream of St. Joseph (1650-55)
Have you noticed that in the Bible, a lot of the time when people get a vision of what God sees for the world it's in a dream? I'm not talking a metaphorical (though very real), Martin Luther King, Jr.-style dream. I'm talking about a literal, I'm-physically-sleeping-when-I-see-it kind of dream. Abraham had one; so did Jacob (actually twice, not counting his vision of God), not to mention Joseph, Jacob's son, Joseph, Mary's husband, and many others. And this isn't just a before-Jesus thing either, because Paul had at least two.
I don't think I've ever heard anyone teach much about acquiring a vision from God by dreaming, perhaps because it's hard to know how to apply it practically. But if we're going to be biblical in our approach to vision, I guess we had better be open to it. Attend to your dreams, because you never know when the Lord is going to show up.